US20030051924A1 - Insert chip of oil-drilling tricone bit, manufacturing method thereof and oil-drilling tricone bit - Google Patents

Insert chip of oil-drilling tricone bit, manufacturing method thereof and oil-drilling tricone bit Download PDF

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US20030051924A1
US20030051924A1 US10/105,012 US10501202A US2003051924A1 US 20030051924 A1 US20030051924 A1 US 20030051924A1 US 10501202 A US10501202 A US 10501202A US 2003051924 A1 US2003051924 A1 US 2003051924A1
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Prior art keywords
cemented carbide
layer
insert
chip
oil
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US6719074B2 (en
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Keiichi Tsuda
Nobuyuki Mori
Hideki Moriguchi
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Japan Oil Gas and Metals National Corp
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Assigned to JAPAN NATIONAL OIL CORPORATION, SUMITOMO ELECTRIC INDUSTRIES, LTD. reassignment JAPAN NATIONAL OIL CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MORI, NOBUYUKI, MORIGUCHI, HIDEKI, TSUDA, KEIICHI
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Assigned to JAPAN OIL, GAS AND METALS NATIONAL CORPORATION reassignment JAPAN OIL, GAS AND METALS NATIONAL CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SUMITOMO ELECTRIC INDUSTRIES, LTD.
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00Drill bits
    • E21B10/46Drill bits characterised by wear resisting parts, e.g. diamond inserts
    • E21B10/56Button-type inserts
    • E21B10/567Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts
    • E21B10/573Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts characterised by support details, e.g. the substrate construction or the interface between the substrate and the cutting element
    • E21B10/5735Interface between the substrate and the cutting element
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00Drill bits
    • E21B10/46Drill bits characterised by wear resisting parts, e.g. diamond inserts
    • E21B10/50Drill bits characterised by wear resisting parts, e.g. diamond inserts the bit being of roller type
    • E21B10/52Drill bits characterised by wear resisting parts, e.g. diamond inserts the bit being of roller type with chisel- or button-type inserts

Definitions

  • the present invention relates to insert chips and a manufacturing method thereof.
  • Insert chips are used as blades (teeth) of a tricone bit which is a tool for drilling an oil well (hereinafter referred to as oil-drilling tricone bit).
  • the insert chips refer to, for example, an inner chip for drilling a well in the vertical direction and a gage pad for drilling the well in the radial direction of the well.
  • the present invention further relates to an oil-drilling tricone bit having the insert chips as described above.
  • a tool called tricone bit is used for drilling an oil well for example.
  • the tricone bit is used for drilling subterranean rocks and thus the tricone bit generally has, as its cutting edges, insert chips made of WC-Co-based cemented carbide with good abrasion resistance.
  • Insert chips for the tricone bit are generally classified into two types, i.e., an inner chip for vertical drilling of an oil well and a gage pad for drilling the oil well in the radial direction.
  • An inner chip and a gage pad are schematically shown in FIGS. 9 and 10 respectively.
  • Japanese Patent Laying-Open No. 5-209488 discloses a rock-drilling button having an ⁇ (eta)-phase core exposed at the top and a surface region having a high Co content that is formed to enclose the ⁇ -phase core, produced by adjusting sintering conditions of cemented carbide.
  • abrasion is alleviated since the exposed ⁇ -phase touches rocks from the start of drilling.
  • the high Co content in the surface region enhances the chipping resistance.
  • the cemented carbide composition containing the ⁇ -phase which is an embrittlement phase is requisite.
  • the ⁇ -phase included in the cemented carbide could be an origin from which the metal is likely to chip off, resulting in deterioration of reliability.
  • Japanese Patent Laying-Open No. 7-150878 discloses an art of improving peeling resistance of the outermost polycrystalline diamond layer of an insert.
  • This insert has a substrate made of sintered tungsten carbide, the outermost surface of a cutting edge of the insert is covered with the polycrystalline diamond layer, and an intermediate layer is provided between the substrate of sintered tungsten carbide and the polycrystalline diamond layer.
  • the intermediate layer is a composite-material layer made of sintered tungsten carbide and polycrystalline diamond.
  • a problem with this art is that the polycrystalline diamond itself has a low toughness which causes any crack in the outermost polycrystalline diamond layer and consequently the crack becomes an origin from which the insert breaks off.
  • Japanese Patent Laying-Open No. 11-12090 discloses a similar art according to which CVD (chemical vapor deposition) is used for coating a surface of a drill bit made of cemented carbide with diamond.
  • CVD chemical vapor deposition
  • the diamond and cemented carbide are different in thermal expansion coefficient which could cause a problem of peeling.
  • Japanese Patent Laying-Open No. 8-170482 proposes a drill bit having a hardness gradient. Specifically, the lowest hardness of a substrate of an insert chip of the drill bit increases gradually toward the leading end of the insert chip. It is noted that the tricone bit includes cone sections in which respective insert chips are fit and a body holding the cone sections, and not only the cone sections rotate but also the body itself rotates for drilling. Accordingly, not only tips of cutting edges of the insert chips but also sides of the cutting edges contribute to drilling. If the art disclosed in Japanese Patent Laying-Open No.
  • the cutting edge has its side where cemented carbide of low hardness, i.e., low abrasion resistance, is exposed, since the insert chip is formed of a stack including cemented carbide materials of different compositions bonded to each other.
  • a resultant problem is that the side of the cutting edge predominantly wears to shorten the lifetime.
  • Japanese National Patent Publication No. 10-511432 proposes an insert chip having a substrate of a cemented carbide and a cutting edge coated with one coating layer of a cemented carbide different from that of the substrate.
  • the coating layer of the cemented carbide has a lower Co content than that of the substrate for improving the abrasion resistance of the insert chip and satisfying the chipping resistance requirement by the substrate. It is known that decrease of Co content of cemented carbide decreases thermal expansion coefficient thereof. Then, if the difference in Co content between the substrate and the coating layer with which the substrate is coated is excessively large, a resultant problem is that the coating cemented carbide layer is peeled off or any crack occurs, for example. Then, according to this art, the coating cemented carbide layer cannot have its Co content greatly different from that of the substrate and thus the improvement of abrasion resistance is limited.
  • One object of the present invention is to provide an insert chip of an oil-drilling tricone bit and a method of manufacturing the insert chip, the insert chip having both of abrasion resistance and chipping resistance. It is also an object of the present invention to provide an oil-drilling tricone bit suitable for drilling rocks which are at greater depths and thus hard to drill.
  • An insert chip of an oil-drilling tricone bit includes, in order to achieve the above-described objects, an insert-chip substrate made of a cemented carbide of a first composition, the substrate including a cylindrical body and a cutting edge for drilling, and includes a cemented carbide coating layer formed of at least two stacked coating layers made of a cemented carbide of a composition different from the first composition, the cemented carbide coating layer covering at least 80% of the surface area of the cutting edge of the insert-chip substrate.
  • the coating layers each have a thickness, at a tip portion of the cutting edge, ranging from 0.1 mm to 2.5 mm and, the total thickness of the cemented carbide coating layer ranges from 1 mm to 5 mm.
  • the coating layers include an outermost cemented carbide layer and at least one coating layer besides the outermost cemented carbide layer and the outermost cemented carbide layer has a hardness higher than that of that at least one coating layer and of the insert-chip substrate.
  • the cemented carbide coating layer covers the whole of the cutting edge.
  • the abrasion resistance can further be improved.
  • those at least two stacked coating layers include, besides the outermost cemented carbide layer, an anti-chipping layer of a composition with a higher Co content than that of the outermost cemented carbide layer or with a larger WC particle size than that of the outermost cemented carbide layer. More preferably, the anti-chipping layer has a composition with a higher Co content than that of the insert-chip substrate. The chipping resistance can thus be improved.
  • the anti-chipping layer which is one of the coating layers is accordingly thin, 2.5 mm or less in thickness. Therefore, resistance to plastic deformation is superior to the deformation resistance obtained by using a cemented carbide with a high Co content for the insert-chip substrate.
  • the anti-chipping layer contains Co particles including special Co particles each elongated in the radial direction of the insert chip in a vertical cross sectional structure of the insert chip and each having a ratio ranging from 3 to 100 that is the length in the radial direction of the insert chip/the length in the axial direction of the insert chip, and the special Co particles constitute at least 5% by volume of the Co particles contained in the anti-chipping layer.
  • the special Co particles constitute at least 5% by volume of the Co particles contained in the anti-chipping layer.
  • the outermost cemented carbide layer contains WC of an average particle size of at most 1 ⁇ m.
  • WC average particle size of at most 1 ⁇ m.
  • the outermost cemented carbide layer includes compressive residual stress.
  • compressive residual stress it is possible to prevent thermal crack and accordingly improve chipping resistance.
  • the outermost cemented carbide layer includes compressive residual stress ranging from 0.05 GPa to 0.80 GPa.
  • compressive residual stress ranging from 0.05 GPa to 0.80 GPa.
  • only the outermost cemented carbide layer among the coating layers contains diamond particles of a particle size ranging from 10 ⁇ m to 100 ⁇ m and the diamond particles constitute 5% to 40% by volume of the outermost cemented carbide layer.
  • diamond particles of a particle size ranging from 10 ⁇ m to 100 ⁇ m and the diamond particles constitute 5% to 40% by volume of the outermost cemented carbide layer.
  • the diamond particles are each covered with at least one of refractory metal and ceramic of at most 1 ⁇ m in thickness.
  • refractory metal and ceramic of at most 1 ⁇ m in thickness.
  • the outermost cemented carbide layer has a micro Vickers hardness of at least 15 GPa.
  • the outermost cemented carbide layer has a micro Vickers hardness of at least 15 GPa.
  • An oil-drilling tricone bit according to the present invention includes, as its cutting edge, in order to achieve the above-described objects, any insert chip of an oil-drilling tricone bit as detailed above.
  • insert chip of an oil-drilling tricone bit provided as a cutting edge, the high abrasion resistance is achieved by the outermost cemented carbide layer and the chipping resistance is improved by remaining coating layer(s) and the insert-chip substrate. Then, the oil-drilling tricone bit has superior drilling performance for rocks at greater depths and thus hard to drill while having a long lifetime.
  • a method of manufacturing an insert chip of an oil-drilling tricone bit includes, in order to achieve the above-described objects, an inserting step of inserting an insert-chip substrate into a die, a stacking step of stacking, on the insert-chip substrate, cemented carbide powder to form a coating layer having a desired thickness after being sintered, and a sintering step of performing electrical pressure sintering, by using a punch inserted into the die, the punch having a depressed end which matches in shape a protruded cutting edge of the insert chip, applying a pressure ranging from 20 MPa to 50 MPa, and controlling the temperature of the punch within a temperature range from 1500° C. to 1800° C.
  • this method it is possible to manufacture an insert chip of an oil-drilling tricone bit having its cemented carbide layer without gross porosity or cavity, without seepage of Co, and without mold breakage.
  • sintering is performed for a period ranging from 5 minutes to 20 minutes.
  • this method it is possible to manufacture an insert chip of an oil-drilling tricone bit having denser cemented carbide without abnormal growth of WC particles.
  • FIG. 1 shows a cross section of an inner chip as an example of insert chips according to a first embodiment of the present invention.
  • FIG. 2 shows a cross section of a gage pad as an example of insert chips according to the first embodiment of the present invention.
  • FIGS. 3 - 5 illustrate first to third steps in a process of manufacturing an insert chip according to an eighth embodiment of the present invention.
  • FIG. 6 is a side view of an insert-chip substrate which is used according to the first embodiment.
  • FIG. 7 shows a cross section of a sample used for Example 1.
  • FIG. 8 schematically shows an oil-drilling tricone bit according to a ninth embodiment of the present invention.
  • FIG. 9 schematically shows a conventional inner chip.
  • FIG. 10 schematically shows a conventional gage pad.
  • insert chips for a tricone bit used for drilling an oil well are classified roughly into two types, i.e., an inner chip for vertically drilling the well and a gage pad for drilling the well in the radial direction of the well.
  • the inner chip (see FIG. 9) and the gage pad (see FIG. 10) are each constituted, in terms of components seen from the outside, generally of a cylindrical portion 1 fit in a body or cone of the tricone bit and a cutting edge 2 for drilling.
  • FIGS. 1 and 2 Exemplary insert chips according to a first embodiment of the present invention are shown in FIGS. 1 and 2, FIG. 1 showing an inner chip and FIG. 2 showing a gage pad.
  • the inner chip and gage pad each include an insert-chip substrate 10 made of a cemented carbide of a composition and a cemented carbide coating layer 20 constituted of at least two stacked coating layers 11 , 12 and 13 made of a cemented carbide of a composition different from the composition of insert-chip substrate 10 .
  • Cemented carbide coating layer 20 is formed to entirely cover a cutting edge 2 of insert-chip substrate 10 .
  • Coating layers 11 , 12 and 13 of the insert chip each have a thickness at a tip portion 3 of cutting edge 2 that ranges from 0.1 mm to 2.5 mm.
  • cemented carbide coating layer 20 ranges from 1 mm to 5 mm.
  • the outermost coating layer 11 among coating layers 11 , 12 and 13 (the outermost coating layer is hereinafter referred to as “outermost cemented carbide layer) is made of a material having the highest hardness in comparison with the hardness of all coating layers and the insert-chip substrate.
  • the insert chip has cemented carbide coating layers 11 , 12 and 13 that cover not only tip portion 3 of cutting edge 2 but also the whole of cutting edge 2 .
  • cemented carbide coating layers 11 , 12 and 13 that cover not only tip portion 3 of cutting edge 2 but also the whole of cutting edge 2 .
  • the composition of coating layer 11 which is the outermost cemented carbide layer has a low Co content relative to that of insert-chip substrate 10 in order to keep abrasion resistance. If insert-chip substrate 10 is directly covered with coating layer 11 , there is a great difference in thermal expansion coefficient between substrate 10 and coating layer 11 and this difference causes a thermal stress possibly resulting in a problem that coating layer 11 is peeled off or any crack occurs.
  • cemented carbide coating layers 12 and 13 having respective Co contents different from each other are provided as intermediate layers between coating layer 11 and substrate 10 . Respective Co contents of coating layers 11 , 12 and 13 are made different from each other to just small degrees so as to lessen the thermal stress.
  • the number of intermediate layers is not limited to two, and one layer or three or more layers may be provided as intermediate layers.
  • the total thickness of cemented carbide coating layers 11 , 12 and 13 that is 1 mm or less does not provide the advantage of abrasion resistance while the total thickness of 5 mm or more deteriorates chipping resistance and thus is not preferred. If each coating layer made of a cemented carbide is less than 0.1 mm in thickness, the outermost cemented carbide layer has a deteriorated abrasion resistance and the intermediate layers do not serve to sufficiently lessen the thermal stress. On the other hand, if the thickness of each coating layer exceeds 2.5 mm, the outermost layer has a deteriorated chipping resistance. Then, preferably, the thickness of each coating layer ranges from 0.1 mm to 2.5 mm.
  • the above-described structure makes it possible for the outermost cemented carbide layer to have a micro Vickers hardness of 15 GPa. It has been known that a cemented carbide having a micro Vickers hardness of at least 15 GPa exhibits an excellent abrasion resistance with respect to rocks that are hard to drill (hard-to-drill rocks). However, the cemented carbide of at least 15 GPa has a relatively low chipping resistance. For this reason, practical use of such a cemented carbide for drilling of hard-to-drill rocks has been difficult.
  • only the outermost thin cemented carbide layer of the insert chip has the micro Vickers hardness of at least 15 GPa, so that the abrasion resistance is kept by this cemented carbide layer while the lack of chipping resistance thereof is compensated for by underlying layers and the substrate of the insert chip. Then, the insert chip excellent in abrasion resistance with respect to hard-to-drill rocks, especially granite, is achieved.
  • the insert chip of the present invention may have its substrate 10 of a cemented carbide composition with a high Co content. However, plastic deformation of this insert chip could occur due to geothermal heat or the like.
  • the insert chip includes a plurality of cemented carbide coating layers and, at least one, except for the outermost cemented carbide layer, of the coating layers has a higher Co content than that of an insert-chip substrate 10 (the higher-Co-content layer is hereinafter referred to as “anti-chipping layer”).
  • This insert chip has its appearance as shown in FIGS. 1 and 2.
  • the anti-chipping layer is any of coating layer 12 and coating layer 13 .
  • the second embodiment is the same as the first embodiment as described above.
  • the above-described structure includes at least one of coating layers that has a higher Co content than that of insert-chip substrate 10 , i.e., anti-chipping layer, and the presence of this anti-chipping layer improves the chipping resistance.
  • anti-chipping layer only one anti-chipping layer among cemented carbide coating layers may have a higher Co content.
  • the maximum total thickness of the coating layers is merely 2.5 mm. Therefore, that one anti-chipping layer, which is a cemented carbide layer having a high Co content, among such thin coating layers, occupies a relatively small part of the entire structure. Accordingly, a higher resistance is achieved to the plastic deformation as compared with the structure having insert-chip substrate 10 made of a cemented carbide with a high Co content.
  • FIGS. 1 and 2 An insert chip according to a third embodiment of the present invention is described.
  • the insert chip has its appearance as shown in FIGS. 1 and 2.
  • the insert chip of the third embodiment is basically the same in structure as that of the second embodiment.
  • an anti-chipping layer includes flat Co particles elongated in the radial direction of the insert chip.
  • Whether or not any Co particle has its shape corresponding to “flat Co particle elongated in the radial direction of the insert chip” is determined according to whether the Co particle has an aspect ratio ranging from 3 to 100 in the vertical cross-sectional constitution of the insert chip.
  • the aspect ratio of the Co particle refers to a ratio between the length in the radial direction of the insert chip and the length in the axial direction of the insert chip.
  • the anti-chipping layer is made of a material which includes special Co particles of at least 5% by volume relative to the entire volume of Co particles of the material.
  • the material of the anti-chipping layer includes at least 5% by volume of special Co particles relative to the entire volume of Co particles in the material. Then, as compared with any material including the same percentage by volume of spherical Co particles as that of special Co particles, the extent to which cracks run can be reduced which considerably improves the chipping resistance. Cracks in the insert chip tend to run in the axial direction of the insert chip. It is accordingly important that special Co particles are present as being elongated radially in the vertical cross-sectional constitution of the insert chip so that the special Co particles are each relatively short in the axial direction of the insert chip. The effect as described above is fully exhibited when the aspect ratio of Co particles ranges from 3 to 100. There is no significant difference in terms of this effect between the anti-chipping layer including Co particles of the aspect ratio of less than 3 and the anti-chipping layer having spherical Co particles. On the other hand, the aspect ratio exceeding 100 lowers the resistance to cracks.
  • FIGS. 1 and 2 An insert chip according to a fourth embodiment of the present invention is described.
  • the insert chip has its appearance as shown in FIGS. 1 and 2.
  • the insert chip of the fourth embodiment is basically the same in structure as that of the third embodiment.
  • One difference is that the outermost cemented carbide layer, according to the fourth embodiment, is made of a cemented carbide material with an average WC particle size of 1 ⁇ m or less.
  • the outermost cemented carbide layer is preferably made of a cemented carbide having WC particles with their average particle size of 1 ⁇ m or less.
  • the insert chip is made remarkably effective for drilling of hard-to-drill rocks.
  • the outermost cemented carbide layer having an average WC particle size of at most 1 ⁇ m enables the insert chip to effectively drill rocks even if the rocks are hard to drill.
  • FIGS. 1 and 2 An insert chip according to a fifth embodiment of the present invention is described.
  • the insert chip has its appearance as shown in FIGS. 1 and 2.
  • the insert chip of the fifth embodiment is basically the same in structure as that described according to the first to fourth embodiments.
  • One difference is that the outermost cemented carbide layer has a compressive residual stress ranging from 0.05 GPa to 0.80 GPa.
  • FIGS. 1 and 2 An insert chip according to a sixth embodiment of the present invention is described.
  • the insert chip has its appearance as shown in FIGS. 1 and 2.
  • the insert chip of the sixth embodiment is basically the same in structure as that described according to the first to fifth embodiments.
  • One difference is that only the outermost cemented carbide layer, among cemented carbide coating layers, contains diamond particles.
  • the size of diamond particles ranges from 10 ⁇ m to 100 ⁇ m and, percentage by volume of the diamond particles relative to the volume of the outermost cemented carbide layer ranges from 5% by volume to 40% by volume.
  • the above-described structure including diamond particles in the outermost cemented carbide layer remarkably enhances the abrasion resistance.
  • the particle size of diamond particles is less than 10 ⁇ m, the abrasion resistance achieved by the inclusion of diamond particles is not significantly different from that achieved without diamond particles in the outermost cemented carbide layer.
  • the diamond particle size exceeds 100 ⁇ m, diamond particles have a reduced surface area which contacts cemented carbide per a volume of a diamond particle and consequently diamond particles are likely to drop off. Then, no satisfactory abrasion resistance is exhibited.
  • the abrasion resistance achieved by less than 5% by volume of diamond particles is not significantly different from the abrasion resistance achieved by cemented carbide only. More than 40% by volume of diamond particles considerably deteriorates the chipping resistance.
  • the structure according to the sixth embodiment is thus preferable
  • FIGS. 1 and 2 An insert chip according to a seventh embodiment of the present invention is described.
  • the insert chip has its appearance as shown in FIGS. 1 and 2.
  • the insert chip of the seventh embodiment is basically the same in structure as that described according to the sixth embodiment.
  • One difference is that diamond particles included in the outermost cemented carbide layer are coated with a refractory metal or ceramic of 1 ⁇ m or less in thickness.
  • Coating of diamond particles with refractory metal or ceramic is especially effective in improvement of the wetting property of diamond particles with respect to cemented carbide.
  • the insert chip according to the seventh embodiment has diamond particles coated with the refractory metal or ceramic of at most 1 ⁇ m in thickness, which increases the degree of adhesion between diamond particles and cemented carbide. This is preferable since diamond particles are unlikely to drop off.
  • a method of manufacturing an insert chip according to an eighth embodiment of the present invention is now described. This manufacturing method is applicable to manufacture of the insert chips as discussed in connection with the embodiments above. Although description here is applied to an inner chip, the description is also applicable to a gage pad.
  • an insert-chip substrate 10 is put in a sintering graphite die 31 .
  • powder 32 a, powder 32 b and powder 32 c of respective cemented carbide compositions are stacked on insert-chip substrate 10 to constitute respective coating layers having predetermined thicknesses respectively after being sintered.
  • a graphite punch 33 is inserted, the punch having its depressed top matching the protruded cutting edge of the insert chip.
  • the applied pressure if the applied pressure is lower than 20 MPa, the pressure is insufficient resulting in any gross porosity or cavity in the cemented carbide layers. If the pressure is higher than 50 MPa, the graphite die could be broken. Then, the applied pressure preferably ranges from 20 MPa to 50 MPa.
  • the sintering temperature is lower than 1500° C., sintering of cemented carbide is impossible.
  • the sintering temperature exceeding 1800° C. causes a problem that Co as a component of the cemented carbide seeps through and appears on the surface of the cemented carbide Therefore, the sintering temperature preferably ranges from 1500° C. to 1800° C.
  • the sintering time is desirably 5 to 20 minutes. If the sintering time is shorter than 5 minutes, dense cemented carbide cannot be produced. On the other hand, if the sintering time is longer than 20 minutes, an abnormal grain growth could occur of WC particles included in the cemented carbide which is not preferable.
  • Insert-chip substrate 10 for a tricone bit as shown in FIG. 6 was prepared. Although the description here is applied to an inner chip, the description is also applicable to a gage pad. Insert-chip substrate 10 was made of a cemented carbide having a composition of WC-20% Co and the WC particle size was 4 ⁇ m. Powder layers were stacked on a cutting edge 2 of insert-chip substrate 10 to constitute a first layer 41 , a second layer 42 and a third layer 43 . Samples B-J were then produced through electrical pressure sintering. The samples had a cross section as shown in FIG. 7. It is noted that the first, second and third layers are named in the order from the one closest to the outermost surface to the one closest to the inside of insert-chip substrate 10 .
  • the samples for evaluation of alloy characteristics were each cut along the central axis thereof and the resultant cross sections were mirror-finished.
  • the thickness of stacked cemented carbide layers each i.e., the thickness of each coating layer
  • the hardness of stacked coating layers each was measured with a micro Vickers hardness meter, and the average hardness was employed as the hardness of each coating layer.
  • sample A was insert-chip substrate 10 itself without coating layer that was used for comparison.
  • Example 2 an insert-chip substrate 10 which is the same as that of Example 1 was prepared. Cemented carbide powder layers were stacked on a cutting edge 2 of insert-chip substrate 10 to form the first to third layers 41 - 43 and then samples K-R were produced by electrical pressure sintering. For each of samples K-R, two samples for tool evaluation and two samples for alloy-characteristic evaluation were produced. Each sample has its cross section as shown in FIG. 7. Table 4 and Table 5 show composition of stacked cemented carbides, thickness of each layer, volume percentage and aspect ratio of special Co particles (defined in the description of the third embodiment) in the third cemented carbide layer having its Co content higher than that of the insert-chip substrate. TABLE 4 COMPOSITION ETC.
  • the samples for evaluation of alloy characteristics were each cut along the central axis thereof and the resultant cross sections were mirror-finished.
  • the thickness of stacked cemented carbide layers each i.e., the thickness of each coating layer
  • a ⁇ 1500 photograph was taken of the constitution of the third layer having a higher Co content than that of the insert-chip substrate, the photograph being taken as an optical-photomicrograph of the structure (field of view: 60 ⁇ m ⁇ 40 ⁇ m).
  • the volume ratio of special Co particles volume ratio of special Co particles to the volume of all Co particles in the third coating layer
  • the aspect ratio of flat Co was determined on the optical-photomicrograph of the structure.
  • sample K was insert-chip substrate 10 itself without coating layer that was used for comparison.
  • Example 3 an insert-chip substrate 10 which is the same as that of Example 1 was prepared. Cemented carbide powder layers were stacked on a cutting edge 2 of substrate 10 to form the first to third layers 41 - 43 and then samples T-Y were produced by electrical pressure sintering. For each of samples T-Y, two samples for tool evaluation and two samples for alloy-characteristic evaluation were produced. Each sample has its cross section as shown in FIG. 7. Table 7 and Table 8 show composition of stacked cemented carbides, thickness of each layer, and compressive residual stress in the first layer which is the outermost cemented carbide layer. TABLE 7 COMPOSITION ETC.
  • the samples for evaluation of alloy characteristics were each cut along the central axis thereof and the resultant cross sections were mirror-finished.
  • the thickness of stacked cemented carbide layers each i.e., the thickness of each coating layer, was measured by means of an optical microscope.
  • the residual stress of WC particles was measured, at a tip portion 48 of the cutting edge of the insert chip, by a residual-stress-measuring method with X-ray sin2 ⁇ .
  • the residual stress of WC was determined for WC face ( 212 ) by using a Young's modulus of 590 GPa and a Poisson ratio of 0.22.
  • sample S was insert-chip substrate 10 itself without coating layer that was used for comparison.
  • the samples for tool evaluation each had a semispherical cutting edge with a radius of 7 mm. Then, an end portion 49 of each sample was partially cut away so as to make the height of the completed insert chip equal to the length of the original insert-chip substrate 10 .
  • the samples for tool evaluation were each press-fit into the leading end of a rock drill, used to drill a hole in granite. An impact test was performed for 5 hours under the conditions that the impact energy was 40 J/shot and the number of shots was 2500/min. After the test, for each sample, the amount of wear in the longitudinal direction of the sample as well as whether any breakage or crack was present or not were checked.
  • Example 4 an insert-chip substrate 10 which is the same as that of Example 1 was prepared. Cemented carbide powder layers were stacked on a cutting edge 2 of substrate 10 to form the first to third layers 41 - 43 and then samples BB-LL were produced by electrical pressure sintering. The first layer 41 of samples DD-LL was formed of cemented carbide powder with which diamond particles were mixed. For each of samples BB-LL, two samples for tool evaluation and two samples for alloy-characteristic evaluation were produced. Each sample has its cross section as shown in FIG. 7.
  • Table 10 and Table 11 show composition of stacked cemented carbides, size of diamond particles in the first layer 41 , volume percentage of the diamond particles relative to the first layer 41 , material with which diamond particles are coated, and composition of respective cemented carbides of the second and third layers.
  • Table 12 shows thickness of each coating layer for example.
  • sample AA was insert-chip substrate 10 itself without coating layer that was used for comparison.
  • the samples for tool evaluation each had a semispherical cutting edge with a radius of 7 mm. Then, an end portion 49 of each sample was partially cut away so as to make the height of the completed insert chip equal to the length of the original insert-chip substrate 10 .
  • the samples for tool evaluation were each press-fit into the leading end of a rock drill, used to drill a hole in granite. An impact test was performed for 5 hours under the conditions that the impact energy was 25 J/shot and the number of shots was 2000/min. After the test, for each sample, the amount of wear in the longitudinal direction of the sample as well as whether any breakage or crack was present or not were checked.
  • This oil-drilling tricone bit 50 has, as shown in FIG. 8, a plurality of rotatable cones 52 attached to an end portion of a body 51 .
  • Three cones 52 are usually attached to one body 51 , and cones 52 are arranged with respective tops that are directed inward and face each other.
  • a plurality of insert chips 53 serving as cutting edges respectively are each inserted from the outer surface of associated cone 52 and secured there.
  • Insert chip 53 here is any of the insert chips described in connection with the first to seventh embodiments.
  • the structure of the oil-drilling tricone bit is illustrated in FIG. 8 by way of example only.
  • the oil-drilling tricone bit intended by the present invention may be any, if the tricone bit has any of insert chips described in connection with the first to seventh embodiments.
  • the shape, number and arrangement of cones as well as the shape of the body are not limited to those shown in FIG. 8.
  • Oil-drilling tricone chip 50 includes insert chips arranged respectively as cutting edges, and a high abrasion resistance is achieved by the outermost cemented carbide coating layers of the insert chips while an improved chipping resistance is achieved by other coating layers and the insert-chip substrate. It is thus possible for the oil-drilling tricone bit to exhibit a high performance in drilling of rocks that are at greater depths and thus hard to drill and still have a long lifetime.
  • the insert chip includes the outermost cemented carbide layer which is one of cemented carbide coating layers each having an appropriate thickness at the tip portion of the cutting edge of the insert chip.
  • the outermost cemented carbide layer has a higher hardness than that of other coating layers and the insert-chip substrate. Accordingly, it is possible to achieve a high abrasion resistance by the outermost cemented carbide layer and simultaneously achieve a high chipping resistance by other coating layers and the insert-chip substrate. Moreover, the thermal stress is reduced by intermediate layers, which prevents peeling and crack of coating layers. The oil-drilling tricone bit having such insert chips is thus appropriate for drilling of hard-to-drill rocks.

Abstract

An insert chip of an oil-drilling tricone bit includes an insert-chip substrate made of a cemented carbide of a first composition, and further includes a cemented carbide coating layer constituted of at least two stacked coating layers made of a cemented carbide of a composition different from the first composition, the cemented carbide coating layer covering the whole of a cutting edge of the insert-chip substrate. The coating layers each have a thickness, at a tip portion of the cutting edge, ranging from 0.1 mm to 2.5 mm and, the total thickness of the cemented carbide coating layer ranges from 1 mm to 5 mm. The coating layers include an outermost cemented carbide layer and at least one coating layer besides the outermost cemented carbide layer and the outermost cemented carbide layer has a hardness higher than that of that at least one coating layer and of the insert-chip substrate.

Description

    BACKGROUND OF THE INVENTION
  • 1. Field of the Invention [0001]
  • The present invention relates to insert chips and a manufacturing method thereof. Insert chips are used as blades (teeth) of a tricone bit which is a tool for drilling an oil well (hereinafter referred to as oil-drilling tricone bit). Specifically, the insert chips refer to, for example, an inner chip for drilling a well in the vertical direction and a gage pad for drilling the well in the radial direction of the well. The present invention further relates to an oil-drilling tricone bit having the insert chips as described above. [0002]
  • 2. Description of the Background Art [0003]
  • A tool called tricone bit is used for drilling an oil well for example. The tricone bit is used for drilling subterranean rocks and thus the tricone bit generally has, as its cutting edges, insert chips made of WC-Co-based cemented carbide with good abrasion resistance. [0004]
  • Insert chips for the tricone bit are generally classified into two types, i.e., an inner chip for vertical drilling of an oil well and a gage pad for drilling the oil well in the radial direction. An inner chip and a gage pad are schematically shown in FIGS. 9 and 10 respectively. [0005]
  • In recent years, oil wells are drilled at increasingly greater depths and accordingly rocks themselves at such great depths are hard to drill. Because of this, insert chips that are cutting edges of the tricone bit wear at earlier stages or some fragments of insert chips are broken (chipped) off from the insert chips (chipping of insert chips). A resultant problem is a shortened lifetime of the tricone bit. Moreover, a considerably costly work is necessary for lifting the tricone bit which reaches the end of its lifetime at several thousand meters below ground and for replacing the tricone bit with new one in order to proceed with drilling. Then, there is a need for further increase in the lifetime of insert chips. [0006]
  • Under the situation as described above, both of abrasion resistance and resistance to chipping (hereinafter chipping resistance) of insert chips must be improved. In general, cemented carbide has a higher hardness when it contains a smaller amount of Co and thus has an improved abrasion resistance, while the smaller amount of Co results in a higher brittleness of the cemented carbide which deteriorates the chipping resistance. In other words, the abrasion resistance and chipping resistance are not compatible with each other [0007]
  • Various arts have been well known that concern the need for increase in the lifetime of insert chips as detailed below. [0008]
  • Japanese Patent Laying-Open No. 5-209488 discloses a rock-drilling button having an η (eta)-phase core exposed at the top and a surface region having a high Co content that is formed to enclose the η-phase core, produced by adjusting sintering conditions of cemented carbide. According to the art disclosed, abrasion is alleviated since the exposed η-phase touches rocks from the start of drilling. On the other hand, the high Co content in the surface region enhances the chipping resistance. A problem with this art is that the cemented carbide composition containing the η-phase which is an embrittlement phase is requisite. In general, the η-phase included in the cemented carbide could be an origin from which the metal is likely to chip off, resulting in deterioration of reliability. [0009]
  • Japanese Patent Laying-Open No. 7-150878 discloses an art of improving peeling resistance of the outermost polycrystalline diamond layer of an insert. This insert has a substrate made of sintered tungsten carbide, the outermost surface of a cutting edge of the insert is covered with the polycrystalline diamond layer, and an intermediate layer is provided between the substrate of sintered tungsten carbide and the polycrystalline diamond layer. The intermediate layer is a composite-material layer made of sintered tungsten carbide and polycrystalline diamond. However, a problem with this art is that the polycrystalline diamond itself has a low toughness which causes any crack in the outermost polycrystalline diamond layer and consequently the crack becomes an origin from which the insert breaks off. [0010]
  • Japanese Patent Laying-Open No. 11-12090 discloses a similar art according to which CVD (chemical vapor deposition) is used for coating a surface of a drill bit made of cemented carbide with diamond. However, the diamond and cemented carbide are different in thermal expansion coefficient which could cause a problem of peeling. [0011]
  • Japanese Patent Laying-Open No. 8-170482 proposes a drill bit having a hardness gradient. Specifically, the lowest hardness of a substrate of an insert chip of the drill bit increases gradually toward the leading end of the insert chip. It is noted that the tricone bit includes cone sections in which respective insert chips are fit and a body holding the cone sections, and not only the cone sections rotate but also the body itself rotates for drilling. Accordingly, not only tips of cutting edges of the insert chips but also sides of the cutting edges contribute to drilling. If the art disclosed in Japanese Patent Laying-Open No. 8-170482 is applied to insert chips of a tricone bit, the cutting edge has its side where cemented carbide of low hardness, i.e., low abrasion resistance, is exposed, since the insert chip is formed of a stack including cemented carbide materials of different compositions bonded to each other. A resultant problem is that the side of the cutting edge predominantly wears to shorten the lifetime. [0012]
  • Japanese National Patent Publication No. 10-511432 proposes an insert chip having a substrate of a cemented carbide and a cutting edge coated with one coating layer of a cemented carbide different from that of the substrate. Specifically, the coating layer of the cemented carbide has a lower Co content than that of the substrate for improving the abrasion resistance of the insert chip and satisfying the chipping resistance requirement by the substrate. It is known that decrease of Co content of cemented carbide decreases thermal expansion coefficient thereof. Then, if the difference in Co content between the substrate and the coating layer with which the substrate is coated is excessively large, a resultant problem is that the coating cemented carbide layer is peeled off or any crack occurs, for example. Then, according to this art, the coating cemented carbide layer cannot have its Co content greatly different from that of the substrate and thus the improvement of abrasion resistance is limited. [0013]
  • As discussed above, various studies have been conducted on insert chips for drilling and drill bits. However, there is still a need for an insert chip, especially an insert chip of an oil-drilling tricone bit, that is suitable for drilling rocks which are at greater depths and accordingly difficult to drill and that has both of abrasion resistance and chipping resistance. [0014]
  • SUMMARY OF THE INVENTION
  • One object of the present invention is to provide an insert chip of an oil-drilling tricone bit and a method of manufacturing the insert chip, the insert chip having both of abrasion resistance and chipping resistance. It is also an object of the present invention to provide an oil-drilling tricone bit suitable for drilling rocks which are at greater depths and thus hard to drill. [0015]
  • An insert chip of an oil-drilling tricone bit according to the present invention includes, in order to achieve the above-described objects, an insert-chip substrate made of a cemented carbide of a first composition, the substrate including a cylindrical body and a cutting edge for drilling, and includes a cemented carbide coating layer formed of at least two stacked coating layers made of a cemented carbide of a composition different from the first composition, the cemented carbide coating layer covering at least 80% of the surface area of the cutting edge of the insert-chip substrate. The coating layers each have a thickness, at a tip portion of the cutting edge, ranging from 0.1 mm to 2.5 mm and, the total thickness of the cemented carbide coating layer ranges from 1 mm to 5 mm. The coating layers include an outermost cemented carbide layer and at least one coating layer besides the outermost cemented carbide layer and the outermost cemented carbide layer has a hardness higher than that of that at least one coating layer and of the insert-chip substrate. By the above-described structure, it is possible to achieve a high abrasion resistance by the outermost cemented carbide coating layer and improve the chipping resistance by other coating layer(s) and the insert-chip substrate. Moreover, intermediate layer(s) lessens thermal stress, which accordingly prevents peeling and crack of the coating layers. [0016]
  • Preferably, the cemented carbide coating layer covers the whole of the cutting edge. Thus, the abrasion resistance can further be improved. [0017]
  • Preferably, those at least two stacked coating layers include, besides the outermost cemented carbide layer, an anti-chipping layer of a composition with a higher Co content than that of the outermost cemented carbide layer or with a larger WC particle size than that of the outermost cemented carbide layer. More preferably, the anti-chipping layer has a composition with a higher Co content than that of the insert-chip substrate. The chipping resistance can thus be improved. The anti-chipping layer which is one of the coating layers is accordingly thin, 2.5 mm or less in thickness. Therefore, resistance to plastic deformation is superior to the deformation resistance obtained by using a cemented carbide with a high Co content for the insert-chip substrate. [0018]
  • Preferably, the anti-chipping layer contains Co particles including special Co particles each elongated in the radial direction of the insert chip in a vertical cross sectional structure of the insert chip and each having a ratio ranging from 3 to 100 that is the length in the radial direction of the insert chip/the length in the axial direction of the insert chip, and the special Co particles constitute at least 5% by volume of the Co particles contained in the anti-chipping layer. Thus, it is possible to prevent any crack from opening and further running and accordingly improve the anti-chipping property. [0019]
  • Preferably, the outermost cemented carbide layer contains WC of an average particle size of at most 1 μm. Thus, it is possible to prevent WC particles from dropping off and accordingly increase the surface area of one WC particle, which improves adhesion between WC and Co. [0020]
  • Preferably, the outermost cemented carbide layer includes compressive residual stress. Thus, it is possible to prevent thermal crack and accordingly improve chipping resistance. [0021]
  • Preferably, the outermost cemented carbide layer includes compressive residual stress ranging from 0.05 GPa to 0.80 GPa. Thus, it is possible to prevent thermal crack from occurring without breakage of the layer itself. [0022]
  • Preferably, only the outermost cemented carbide layer among the coating layers contains diamond particles of a particle size ranging from 10 μm to 100 μm and the diamond particles constitute 5% to 40% by volume of the outermost cemented carbide layer. Thus, it is possible to enhance abrasion resistance relative to cemented carbide while diamond particles are unlikely to drop off. [0023]
  • Preferably, the diamond particles are each covered with at least one of refractory metal and ceramic of at most 1 μm in thickness. Thus, it is possible to improve the wetting property between the diamond particles and cemented carbide and accordingly improve the adhesion property therebetween. [0024]
  • Preferably, the outermost cemented carbide layer has a micro Vickers hardness of at least 15 GPa. Thus, it is possible to improve the abrasion resistance by the outermost cemented carbide layer with the chipping resistance maintained by those layers under the outermost layer. [0025]
  • An oil-drilling tricone bit according to the present invention includes, as its cutting edge, in order to achieve the above-described objects, any insert chip of an oil-drilling tricone bit as detailed above. By “insert chip of an oil-drilling tricone bit” provided as a cutting edge, the high abrasion resistance is achieved by the outermost cemented carbide layer and the chipping resistance is improved by remaining coating layer(s) and the insert-chip substrate. Then, the oil-drilling tricone bit has superior drilling performance for rocks at greater depths and thus hard to drill while having a long lifetime. [0026]
  • A method of manufacturing an insert chip of an oil-drilling tricone bit includes, in order to achieve the above-described objects, an inserting step of inserting an insert-chip substrate into a die, a stacking step of stacking, on the insert-chip substrate, cemented carbide powder to form a coating layer having a desired thickness after being sintered, and a sintering step of performing electrical pressure sintering, by using a punch inserted into the die, the punch having a depressed end which matches in shape a protruded cutting edge of the insert chip, applying a pressure ranging from 20 MPa to 50 MPa, and controlling the temperature of the punch within a temperature range from 1500° C. to 1800° C. By this method, it is possible to manufacture an insert chip of an oil-drilling tricone bit having its cemented carbide layer without gross porosity or cavity, without seepage of Co, and without mold breakage. [0027]
  • Preferably, in the sintering step, sintering is performed for a period ranging from 5 minutes to 20 minutes. By this method, it is possible to manufacture an insert chip of an oil-drilling tricone bit having denser cemented carbide without abnormal growth of WC particles. [0028]
  • The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.[0029]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 shows a cross section of an inner chip as an example of insert chips according to a first embodiment of the present invention. [0030]
  • FIG. 2 shows a cross section of a gage pad as an example of insert chips according to the first embodiment of the present invention. [0031]
  • FIGS. [0032] 3-5 illustrate first to third steps in a process of manufacturing an insert chip according to an eighth embodiment of the present invention.
  • FIG. 6 is a side view of an insert-chip substrate which is used according to the first embodiment. [0033]
  • FIG. 7 shows a cross section of a sample used for Example 1. [0034]
  • FIG. 8 schematically shows an oil-drilling tricone bit according to a ninth embodiment of the present invention. [0035]
  • FIG. 9 schematically shows a conventional inner chip. [0036]
  • FIG. 10 schematically shows a conventional gage pad.[0037]
  • DESCRIPTION OF THE PREFERRED EMBODIMENTS FIRST EMBODIMENT
  • As described above, insert chips for a tricone bit used for drilling an oil well (hereinafter simply referred to as “tricone bit”) are classified roughly into two types, i.e., an inner chip for vertically drilling the well and a gage pad for drilling the well in the radial direction of the well. The inner chip (see FIG. 9) and the gage pad (see FIG. 10) are each constituted, in terms of components seen from the outside, generally of a [0038] cylindrical portion 1 fit in a body or cone of the tricone bit and a cutting edge 2 for drilling.
  • Exemplary insert chips according to a first embodiment of the present invention are shown in FIGS. 1 and 2, FIG. 1 showing an inner chip and FIG. 2 showing a gage pad. The inner chip and gage pad each include an insert-[0039] chip substrate 10 made of a cemented carbide of a composition and a cemented carbide coating layer 20 constituted of at least two stacked coating layers 11, 12 and 13 made of a cemented carbide of a composition different from the composition of insert-chip substrate 10. Cemented carbide coating layer 20 is formed to entirely cover a cutting edge 2 of insert-chip substrate 10. Coating layers 11, 12 and 13 of the insert chip each have a thickness at a tip portion 3 of cutting edge 2 that ranges from 0.1 mm to 2.5 mm. The entire thickness of cemented carbide coating layer 20 ranges from 1 mm to 5 mm. The outermost coating layer 11 among coating layers 11, 12 and 13 (the outermost coating layer is hereinafter referred to as “outermost cemented carbide layer) is made of a material having the highest hardness in comparison with the hardness of all coating layers and the insert-chip substrate.
  • According to the first embodiment, the insert chip has cemented carbide coating layers [0040] 11, 12 and 13 that cover not only tip portion 3 of cutting edge 2 but also the whole of cutting edge 2. This is because, during a drilling operation of the tricone bit, cone sections with insert chips being fit therein of the tricone bit rotate, and accordingly both of tip portion 3 and a side portion 4 of cutting edge 2 contribute to drilling. In consideration of practical use, preferably at least 80% of the surface area of cutting edge 2 is covered with the coating layers. In particular, preferably the whole of cutting edge 2 is covered.
  • The composition of [0041] coating layer 11 which is the outermost cemented carbide layer has a low Co content relative to that of insert-chip substrate 10 in order to keep abrasion resistance. If insert-chip substrate 10 is directly covered with coating layer 11, there is a great difference in thermal expansion coefficient between substrate 10 and coating layer 11 and this difference causes a thermal stress possibly resulting in a problem that coating layer 11 is peeled off or any crack occurs. In order to avoid this problem, cemented carbide coating layers 12 and 13 having respective Co contents different from each other are provided as intermediate layers between coating layer 11 and substrate 10. Respective Co contents of coating layers 11, 12 and 13 are made different from each other to just small degrees so as to lessen the thermal stress. Although there are two intermediate layers provided between substrate 10 and the outermost cemented carbide layer according to this embodiment, the number of intermediate layers is not limited to two, and one layer or three or more layers may be provided as intermediate layers.
  • However, the total thickness of cemented carbide coating layers [0042] 11, 12 and 13 that is 1 mm or less does not provide the advantage of abrasion resistance while the total thickness of 5 mm or more deteriorates chipping resistance and thus is not preferred. If each coating layer made of a cemented carbide is less than 0.1 mm in thickness, the outermost cemented carbide layer has a deteriorated abrasion resistance and the intermediate layers do not serve to sufficiently lessen the thermal stress. On the other hand, if the thickness of each coating layer exceeds 2.5 mm, the outermost layer has a deteriorated chipping resistance. Then, preferably, the thickness of each coating layer ranges from 0.1 mm to 2.5 mm.
  • The above-described structure makes it possible for the outermost cemented carbide layer to have a micro Vickers hardness of 15 GPa. It has been known that a cemented carbide having a micro Vickers hardness of at least 15 GPa exhibits an excellent abrasion resistance with respect to rocks that are hard to drill (hard-to-drill rocks). However, the cemented carbide of at least 15 GPa has a relatively low chipping resistance. For this reason, practical use of such a cemented carbide for drilling of hard-to-drill rocks has been difficult. On the other hand, according to this embodiment, only the outermost thin cemented carbide layer of the insert chip has the micro Vickers hardness of at least 15 GPa, so that the abrasion resistance is kept by this cemented carbide layer while the lack of chipping resistance thereof is compensated for by underlying layers and the substrate of the insert chip. Then, the insert chip excellent in abrasion resistance with respect to hard-to-drill rocks, especially granite, is achieved. [0043]
  • SECOND EMBODIMENT
  • An insert chip according to a second embodiment of the present invention is described now. In order to increase the rate of penetration (the distance the tricone bit penetrates or drills any rock formation per unit time), the chipping resistance of insert chips must be enhanced. Then, for enhancement of the chipping resistance, the insert chip of the present invention may have its [0044] substrate 10 of a cemented carbide composition with a high Co content. However, plastic deformation of this insert chip could occur due to geothermal heat or the like.
  • According to the second embodiment of the present invention, the insert chip includes a plurality of cemented carbide coating layers and, at least one, except for the outermost cemented carbide layer, of the coating layers has a higher Co content than that of an insert-chip substrate [0045] 10 (the higher-Co-content layer is hereinafter referred to as “anti-chipping layer”). This insert chip has its appearance as shown in FIGS. 1 and 2. Then, the anti-chipping layer is any of coating layer 12 and coating layer 13. Regarding details of the structure except for those described above, the second embodiment is the same as the first embodiment as described above.
  • The above-described structure includes at least one of coating layers that has a higher Co content than that of insert-[0046] chip substrate 10, i.e., anti-chipping layer, and the presence of this anti-chipping layer improves the chipping resistance. In this case, only one anti-chipping layer among cemented carbide coating layers may have a higher Co content. The maximum total thickness of the coating layers is merely 2.5 mm. Therefore, that one anti-chipping layer, which is a cemented carbide layer having a high Co content, among such thin coating layers, occupies a relatively small part of the entire structure. Accordingly, a higher resistance is achieved to the plastic deformation as compared with the structure having insert-chip substrate 10 made of a cemented carbide with a high Co content.
  • THIRD EMBODIMENT
  • An insert chip according to a third embodiment of the present invention is described. The insert chip has its appearance as shown in FIGS. 1 and 2. The insert chip of the third embodiment is basically the same in structure as that of the second embodiment. One difference is that an anti-chipping layer includes flat Co particles elongated in the radial direction of the insert chip. Whether or not any Co particle has its shape corresponding to “flat Co particle elongated in the radial direction of the insert chip” is determined according to whether the Co particle has an aspect ratio ranging from 3 to 100 in the vertical cross-sectional constitution of the insert chip. Here, the aspect ratio of the Co particle refers to a ratio between the length in the radial direction of the insert chip and the length in the axial direction of the insert chip. Any Co particle corresponding to “flat Co particle elongated in the radial direction of the insert chip” is hereinafter referred to as “special Co particle.” According to the third embodiment, the anti-chipping layer is made of a material which includes special Co particles of at least 5% by volume relative to the entire volume of Co particles of the material. [0047]
  • According to the third embodiment, the material of the anti-chipping layer includes at least 5% by volume of special Co particles relative to the entire volume of Co particles in the material. Then, as compared with any material including the same percentage by volume of spherical Co particles as that of special Co particles, the extent to which cracks run can be reduced which considerably improves the chipping resistance. Cracks in the insert chip tend to run in the axial direction of the insert chip. It is accordingly important that special Co particles are present as being elongated radially in the vertical cross-sectional constitution of the insert chip so that the special Co particles are each relatively short in the axial direction of the insert chip. The effect as described above is fully exhibited when the aspect ratio of Co particles ranges from 3 to 100. There is no significant difference in terms of this effect between the anti-chipping layer including Co particles of the aspect ratio of less than 3 and the anti-chipping layer having spherical Co particles. On the other hand, the aspect ratio exceeding 100 lowers the resistance to cracks. [0048]
  • FOURTH EMBODIMENT
  • An insert chip according to a fourth embodiment of the present invention is described. The insert chip has its appearance as shown in FIGS. 1 and 2. The insert chip of the fourth embodiment is basically the same in structure as that of the third embodiment. One difference is that the outermost cemented carbide layer, according to the fourth embodiment, is made of a cemented carbide material with an average WC particle size of 1 μm or less. [0049]
  • In some cases, insert chips used for drilling hard-to-drill rocks wear due to the fact that WC particles in the cemented carbide drop off therefrom. Then, WC particles are effectively reduced in size as small as possible to increase the surface area of one WC particle and thus enhance the adhesion between WC particles and Co. More specifically, the outermost cemented carbide layer is preferably made of a cemented carbide having WC particles with their average particle size of 1 μm or less. In this way, the insert chip is made remarkably effective for drilling of hard-to-drill rocks. According to the fourth embodiment, the outermost cemented carbide layer having an average WC particle size of at most 1 μm enables the insert chip to effectively drill rocks even if the rocks are hard to drill. [0050]
  • FIFTH EMBODIMENT
  • An insert chip according to a fifth embodiment of the present invention is described. The insert chip has its appearance as shown in FIGS. 1 and 2. The insert chip of the fifth embodiment is basically the same in structure as that described according to the first to fourth embodiments. One difference is that the outermost cemented carbide layer has a compressive residual stress ranging from 0.05 GPa to 0.80 GPa. [0051]
  • The presence of compressive residual stress on WC particles in the outermost cemented carbide layer, which is one of coating layers made of cemented carbide is considerably effective in improving the chipping resistance of the insert chip, since the presence of compressive residual stress effectively prevents thermal checks or cracks from appearing. However, the compressive residual stress of less than 0.05 GPa on WC particles does not provide such an advantage while the compressive residual stress exceeding 0.80 GPa is excessively high which results in breakage of particles themselves. The range of residual stress of the fifth embodiment is thus preferable. [0052]
  • SIXTH EMBODIMENT
  • An insert chip according to a sixth embodiment of the present invention is described. The insert chip has its appearance as shown in FIGS. 1 and 2. The insert chip of the sixth embodiment is basically the same in structure as that described according to the first to fifth embodiments. One difference is that only the outermost cemented carbide layer, among cemented carbide coating layers, contains diamond particles. The size of diamond particles ranges from 10 μm to 100 μm and, percentage by volume of the diamond particles relative to the volume of the outermost cemented carbide layer ranges from 5% by volume to 40% by volume. [0053]
  • The above-described structure including diamond particles in the outermost cemented carbide layer remarkably enhances the abrasion resistance. Here, if the particle size of diamond particles is less than 10 μm, the abrasion resistance achieved by the inclusion of diamond particles is not significantly different from that achieved without diamond particles in the outermost cemented carbide layer. On the other hand, if the diamond particle size exceeds 100 μm, diamond particles have a reduced surface area which contacts cemented carbide per a volume of a diamond particle and consequently diamond particles are likely to drop off. Then, no satisfactory abrasion resistance is exhibited. Further, the abrasion resistance achieved by less than 5% by volume of diamond particles is not significantly different from the abrasion resistance achieved by cemented carbide only. More than 40% by volume of diamond particles considerably deteriorates the chipping resistance. The structure according to the sixth embodiment is thus preferable [0054]
  • SEVENTH EMBODIMENT
  • An insert chip according to a seventh embodiment of the present invention is described. The insert chip has its appearance as shown in FIGS. 1 and 2. The insert chip of the seventh embodiment is basically the same in structure as that described according to the sixth embodiment. One difference is that diamond particles included in the outermost cemented carbide layer are coated with a refractory metal or ceramic of 1 μm or less in thickness. [0055]
  • Coating of diamond particles with refractory metal or ceramic is especially effective in improvement of the wetting property of diamond particles with respect to cemented carbide. The insert chip according to the seventh embodiment has diamond particles coated with the refractory metal or ceramic of at most 1 μm in thickness, which increases the degree of adhesion between diamond particles and cemented carbide. This is preferable since diamond particles are unlikely to drop off. [0056]
  • EIGHTH EMBODIMENT
  • A method of manufacturing an insert chip according to an eighth embodiment of the present invention is now described. This manufacturing method is applicable to manufacture of the insert chips as discussed in connection with the embodiments above. Although description here is applied to an inner chip, the description is also applicable to a gage pad. [0057]
  • Referring to FIG. 3, an insert-[0058] chip substrate 10 is put in a sintering graphite die 31. Referring to FIG. 4, powder 32 a, powder 32 b and powder 32 c of respective cemented carbide compositions are stacked on insert-chip substrate 10 to constitute respective coating layers having predetermined thicknesses respectively after being sintered. Then, as shown in FIG. 5, a graphite punch 33 is inserted, the punch having its depressed top matching the protruded cutting edge of the insert chip. By electrical pressure sintering with the applied pressure ranging from 20 MPa to 50 MPa and with the temperature of graphite punch 33 controlled so that the temperature ranges from 1500° C. to 1800° C., the insert chip as described in connection with each embodiment is produced.
  • According to this manufacturing method, if the applied pressure is lower than 20 MPa, the pressure is insufficient resulting in any gross porosity or cavity in the cemented carbide layers. If the pressure is higher than 50 MPa, the graphite die could be broken. Then, the applied pressure preferably ranges from 20 MPa to 50 MPa. [0059]
  • If the sintering temperature is lower than 1500° C., sintering of cemented carbide is impossible. On the other hand, the sintering temperature exceeding 1800° C. causes a problem that Co as a component of the cemented carbide seeps through and appears on the surface of the cemented carbide Therefore, the sintering temperature preferably ranges from 1500° C. to 1800° C. [0060]
  • Manufacturing under the conditions according to this embodiment is thus desirable. [0061]
  • The sintering time is desirably 5 to 20 minutes. If the sintering time is shorter than 5 minutes, dense cemented carbide cannot be produced. On the other hand, if the sintering time is longer than 20 minutes, an abnormal grain growth could occur of WC particles included in the cemented carbide which is not preferable. [0062]
  • Insert chips according to the above-discussed embodiments were actually manufactured and some experiments were conducted thereon. Experimental results are hereinafter described in connection with “Examples.”[0063]
  • EXAMPLE 1
  • An insert-[0064] chip substrate 10 for a tricone bit as shown in FIG. 6 was prepared. Although the description here is applied to an inner chip, the description is also applicable to a gage pad. Insert-chip substrate 10 was made of a cemented carbide having a composition of WC-20% Co and the WC particle size was 4 μm. Powder layers were stacked on a cutting edge 2 of insert-chip substrate 10 to constitute a first layer 41, a second layer 42 and a third layer 43. Samples B-J were then produced through electrical pressure sintering. The samples had a cross section as shown in FIG. 7. It is noted that the first, second and third layers are named in the order from the one closest to the outermost surface to the one closest to the inside of insert-chip substrate 10.
  • For each of samples B-J, two samples for tool evaluation and two samples for alloy-characteristic evaluation were prepared. Composition of stacked cemented carbides, thickness and hardness of each layer, and sintering conditions are shown in Table 1 and Table 2. [0065]
    TABLE 1
    COMPOSITION ETC. OF EXAMPLE 1 SAMPLES
    Composition of 1st Composition of 2nd Composition of 3rd
    cemented carbide cemented carbide cemented carbide Sintering
    layer layer layer Applied temperature of
    (average WC particle (average WC particle (average WC particle pressure upper punch
    Sample size) size) size) (MPa) (° C.)
    *A  no 1st layer no 2nd layer no 3rd layer
    *B  WC (2 μm)-10% Co no 2nd layer no 3rd layer 40 1700
    C WC (2 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 40 1700
    D WC (2 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 22 1780
    E WC (1 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 48 1520
    *F  WC (2 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 40 1700
    *G  WC (2 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 40 1700
    H WC (2 μm)-5% Co  WC (2 μm)-15% Co no 3rd layer 40 1400
    I WC (2 μm)-10% Co WC (2 μm)-15% Co WC (4 μm)-22% Co 25 1600
    J   WC (0.7 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 30 1500
  • [0066]
    TABLE 2
    COATING-LAYER THICKNESS ETC. OF EXAMPLE 1 SAMPLES
    Hardness Hardness
    Thickness Thickness Thickness Hardness of 2nd of 3rd
    of 1st layer of 2nd of 3rd of 1st layer layer layer
    Sample (mm) layer (mm) layer (mm) (GPa) (GPa) (GPa)
    *A  0 0 0
    *B  5 0 0 14.5
    C 2.5 2.5 0 14.7 13.5
    D 0.5 0.5 0 14.6 13.4
    E 1 1 0 16.5 13.5
    *F  0.3 0.3 0 14.3 13.6
    *G 3 3 0 14.5 13.6
    H 0.1 1 0 18.3 13.4
    I 1 1 1 14.6 13.5 7.5
    J 1 1 0 18.5 13.8
  • The samples for evaluation of alloy characteristics were each cut along the central axis thereof and the resultant cross sections were mirror-finished. On the central axis of the mirror-finished cross section, the thickness of stacked cemented carbide layers each, i.e., the thickness of each coating layer, was measured by means of an optical microscope. Further, at five points on the central axis of the cross section, the hardness of stacked coating layers each was measured with a micro Vickers hardness meter, and the average hardness was employed as the hardness of each coating layer. [0067]
  • It is noted that sample A was insert-[0068] chip substrate 10 itself without coating layer that was used for comparison.
  • The samples for tool evaluation were press-fit into the leading end of a rock drill, used to drill a hole in granite. An impact test was performed for 5 hours under the conditions that the impact energy was 30 J/shot and the number of shots was 2000/min. After the test, for each sample, the amount of wear in the longitudinal direction of the sample as well as whether any breakage or crack was present or not were checked. [0069]
  • Results of this test are shown in Table 3. [0070]
    TABLE 3
    DRILL TEST RESULTS OF SAMPLES A-J
    Wear amount Damage etc. to sample after
    Sample (mm) test
    *A  5.8 normal wear
    *B  4.9 1st layer peeled in 2 hours
    C 1.2 normal wear
    D 1.3 normal wear
    E 1.1 normal wear
    *F  4.5 normal wear
    *G  4.2 1st layer peeled in 4 hours
    H 0.6 normal wear
    I 1.3 normal wear
    J 0.5 normal wear
  • EXAMPLE 2
  • For Example 2, an insert-[0071] chip substrate 10 which is the same as that of Example 1 was prepared. Cemented carbide powder layers were stacked on a cutting edge 2 of insert-chip substrate 10 to form the first to third layers 41-43 and then samples K-R were produced by electrical pressure sintering. For each of samples K-R, two samples for tool evaluation and two samples for alloy-characteristic evaluation were produced. Each sample has its cross section as shown in FIG. 7. Table 4 and Table 5 show composition of stacked cemented carbides, thickness of each layer, volume percentage and aspect ratio of special Co particles (defined in the description of the third embodiment) in the third cemented carbide layer having its Co content higher than that of the insert-chip substrate.
    TABLE 4
    COMPOSITION ETC. OF EXAMPLE 2 SAMPLES
    Composition of 1st Composition of 2nd Composition of 3rd
    cemented carbide cemented carbide cemented carbide Sintering
    layer layer layer Applied temperature of
    (average WC particle (average WC particle (average WC particle pressure upper punch
    Sample size) size) size) (MPa) (° C.)
    *K  no 1st layer no 2nd layer no 3rd layer
    *L  WC (2 μm)-10% Co no 2nd layer no 3rd layer 40 1700
    M WC (1 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 48 1520
    N WC (2 μm)-10% Co WC (2 μm)-15% Co WC (4 μm)-22% Co 25 1600
    O WC (2 μm)-10% Co WC (2 μm)-15% Co WC (4 μm)-22% Co 35 1600
    P WC (2 μm)-10% Co WC (2 μm)-15% Co WC (4 μm)-22% Co 40 1600
    Q WC (2 μm)-10% Co WC (2 μm)-15% Co WC (4 μm)-22% Co 45 1600
    R WC (2 μm)-10% Co WC (2 μm)-15% Co WC (4 μm)-22% Co 48 1600
  • [0072]
    TABLE 5
    COATING-LAYER THICKNESS ETC. OF EXAMPLE 2 SAMPLES
    Flat Co
    Thickness Thickness Thickness ratio in 3rd
    of 1st layer of 2nd layer of 3rd layer layer Aspect ratio
    Sample (mm) (mm) (mm) (%) in 3rd layer
    *K  0 0 0
    *L  5 0 0
    M 1 1 0
    N 1 1 1  2  6
    O 1 1 1 48 20
    P 1 1 1 55 80
    Q 1 1 1 87 90
    R 1 1 1 98 110
  • The samples for evaluation of alloy characteristics were each cut along the central axis thereof and the resultant cross sections were mirror-finished. On the central axis of the mirror-finished cross section, the thickness of stacked cemented carbide layers each, i.e., the thickness of each coating layer, was measured by means of an optical microscope. Further, on the central axis of the cross section, a×1500 photograph was taken of the constitution of the third layer having a higher Co content than that of the insert-chip substrate, the photograph being taken as an optical-photomicrograph of the structure (field of view: 60 μm×40 μm). By image processing, the volume ratio of special Co particles (volume ratio of special Co particles to the volume of all Co particles in the third coating layer) was determined. In addition, the aspect ratio of flat Co was determined on the optical-photomicrograph of the structure. [0073]
  • It is noted that sample K was insert-[0074] chip substrate 10 itself without coating layer that was used for comparison.
  • It was confirmed that the samples for tool evaluation each had a semispherical cutting edge with a radius of 7 mm. Then, an [0075] end portion 49 of each sample was partially cut away so as to make the height of the completed insert chip equal to the length of the original insert-chip substrate 10.
  • The samples for tool evaluation were each press-fit into the leading end of a rock drill, used to drill a hole in granite. An impact test was performed for 5 hours under the conditions that the impact energy was 50 J/shot and the number of shots was 2000/min. After the test, for each sample, the amount of wear in the longitudinal direction of the sample as well as whether any breakage or crack was present or not were checked. [0076]
  • Results of this test are shown in Table 6. [0077]
    TABLE 6
    DRILL TEST RESULTS OF SAMPLES K-R
    Wear amount
    Sample (mm) Damage etc. to sample after test
    *K  unmeasurable test stopped as considerably
    deformed in 1 hour
    *L  unmeasurable badly damaged in 0.5 hour
    M 2.8 chipping
    N 2.2 chipping
    O 2.1 tiny cracks
    P 1.5 normal wear
    Q 1.4 normal wear
    R 2.1 tiny cracks
  • EXAMPLE 3
  • For Example 3, an insert-[0078] chip substrate 10 which is the same as that of Example 1 was prepared. Cemented carbide powder layers were stacked on a cutting edge 2 of substrate 10 to form the first to third layers 41-43 and then samples T-Y were produced by electrical pressure sintering. For each of samples T-Y, two samples for tool evaluation and two samples for alloy-characteristic evaluation were produced. Each sample has its cross section as shown in FIG. 7. Table 7 and Table 8 show composition of stacked cemented carbides, thickness of each layer, and compressive residual stress in the first layer which is the outermost cemented carbide layer.
    TABLE 7
    COMPOSITION ETC. OF EXAMPLE 3 SAMPLES
    Composition of 1st Composition of 2nd Composition of 3rd
    cemented carbide cemented carbide cemented carbide Sintering
    layer layer layer Applied temperature of
    (average WC particle (average WC particle (average WC particle pressure upper punch
    Sample size) size) size) (MPa) (° C.)
    *S  no 1st layer no 2nd layer no 3rd layer
    *T  WC (2 μm)-10% Co no 2nd layer no 3rd layer 40 1700
    U WC (1 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 40 1700
    V WC (1 μm)-10% Co WC (2 μm)-15% Co no 3rd layer 40 1700
    W WC (1 μm)-10% Co WC (2 μm)-18% Co no 3rd layer 40 1700
    X WC (1 μm)-5% Co  WC (2 μm)-15% Co no 3rd layer 40 1700
    Y WC (1 μm)-5% Co  WC (2 μm)-15% Co no 3rd layer 40 1700
  • [0079]
    TABLE 8
    COATING-LAYER THICKNESS ETC. OF EXAMPLE 3 SAMPLES
    Thickness Thickness Thickness Compression
    of 1st layer of 2nd layer of 3rd layer pressure in 1st layer
    Sample (mm) (mm) (mm) (GPa)
    *S  0 0 0 0
    *T  5 0 0 0
    U 1 1 0 0.04
    V 0.7 1 0 0.15
    W 0.8 1 0 0.45
    X 0.7 1 0 0.79
    Y 0.6 1 0 0.85
  • The samples for evaluation of alloy characteristics were each cut along the central axis thereof and the resultant cross sections were mirror-finished. On the central axis of the mirror-finished cross section, the thickness of stacked cemented carbide layers each, i.e., the thickness of each coating layer, was measured by means of an optical microscope. Further, the residual stress of WC particles was measured, at a [0080] tip portion 48 of the cutting edge of the insert chip, by a residual-stress-measuring method with X-ray sin2φ. The residual stress of WC was determined for WC face (212) by using a Young's modulus of 590 GPa and a Poisson ratio of 0.22.
  • It is noted that sample S was insert-[0081] chip substrate 10 itself without coating layer that was used for comparison.
  • It was confirmed that the samples for tool evaluation each had a semispherical cutting edge with a radius of 7 mm. Then, an [0082] end portion 49 of each sample was partially cut away so as to make the height of the completed insert chip equal to the length of the original insert-chip substrate 10. The samples for tool evaluation were each press-fit into the leading end of a rock drill, used to drill a hole in granite. An impact test was performed for 5 hours under the conditions that the impact energy was 40 J/shot and the number of shots was 2500/min. After the test, for each sample, the amount of wear in the longitudinal direction of the sample as well as whether any breakage or crack was present or not were checked.
  • Results of this test are shown in Table 9. [0083]
    TABLE 9
    DRILL TEST RESULTS OF SAMPLES S-Y
    Wear amount
    Sample (mm) Damage etc. to sample after test
    *S  unmeasurable test stopped as being considerably
    deformed in 2 hours
    *T  unmeasurable badly damaged in 1 hour
    U 3.3 tiny cracks
    V 2.1 normal wear
    W 2.2 normal wear
    X 2.1 normal wear
    Y 3.1 tiny cracks
  • EXAMPLE 4
  • For Example 4, an insert-[0084] chip substrate 10 which is the same as that of Example 1 was prepared. Cemented carbide powder layers were stacked on a cutting edge 2 of substrate 10 to form the first to third layers 41-43 and then samples BB-LL were produced by electrical pressure sintering. The first layer 41 of samples DD-LL was formed of cemented carbide powder with which diamond particles were mixed. For each of samples BB-LL, two samples for tool evaluation and two samples for alloy-characteristic evaluation were produced. Each sample has its cross section as shown in FIG. 7. Table 10 and Table 11 show composition of stacked cemented carbides, size of diamond particles in the first layer 41, volume percentage of the diamond particles relative to the first layer 41, material with which diamond particles are coated, and composition of respective cemented carbides of the second and third layers. Table 12 shows thickness of each coating layer for example.
    TABLE 10
    State of diamond in 1st layer
    Particle size coating thickness
    Sample Composition of 1st layer (μm) vol % Coating material (μm)
    *AA  no 1st layer
    *BB  cemented carbide
    CC cemented carbide
    DD cemented carbide + diamond 11 29 no coating
    EF cemented carbide + diamond 98 6 no coating
    FF cemented carbide + diamond 50 20 no coating
    GG cemented carbide + diamond 50 20 metal W 0.5
    HH cemented carbide + diamond 50 20 SiC 0.7
    II cemented carbide + diamond 50 20 SiC 0.2
    JJ cemented carbide + diamond 70 20 no coating
    KK cemented carbide + diamond 5 25 no coating
    LL cemented carbide + diamond 120 2 no coating
  • [0085]
    TABLE 11
    2ND/3RD LAYER COMPOSITION ETC. OF EXAMPLE 4 SAMPLES
    Sintering
    Composition of 2nd Composition of 3rd Applied temperature of
    cemented carbide layer cemented carbide layer pressure upper punch
    Sample (average WC particle size) (average WC particle size) (MPa) (° C.)
    *AA  no 2nd layer no 3rd layer
    *BB  no 2nd layer no 3rd layer 40 1700
    CC WC (2 μm)-15% Co no 3rd layer 40 1650
    DD WC (2 μm)-15% Co no 3rd layer 25 1600
    EE WC (2 μm)-15% Co no 3rd layer 35 1550
    FF WC (2 μm)-15% Co no 3rd layer 40 1700
    GG WC (2 μm)-15% Co no 3rd layer 40 1700
    HH WC (2 μm)-15% Co no 3rd layer 40 1700
    II WC (2 μm)-25% Co WC (2 μm)-15% Co 40 1700
    JJ WC (2 μm)-15% Co no 3rd layer 40 1700
    KK WC (2 μm)-15% Co no 3rd layer 40 1700
    LL WC (2 μm)-15% Co no 3rd layer 40 1700
  • [0086]
    TABLE 12
    Thickness of Thickness Thickness of 3rd Hardness of 1st Compression
    1st layer of 2nd layer layer layer stress in 1st layer
    Sample (mm) (mm) (mm) (GPa) (GPa)
    *AA  0 0 no 3rd layer 0
    *BB  5 0 no 3rd layer 13.5 0
    CC 1 1 no 3rd layer 13.5 0.04
    DD 1 1 no 3rd layer 16.8 0.5
    EE 1 1 no 3rd layer 17.2 0.7
    FF 1 1 no 3rd layer 17 0.68
    GG 1 1 no 3rd layer 17 0.45
    HH 1 1 no 3rd layer 16.9 0.45
    II 1 1 1 17.3 0.38
    JJ 1 1 no 3rd layer 20 0.37
    KK 1 1 no 3rd layer 22 0.37
    LL 1 1 no 3rd layer 17 0.35
  • The samples for evaluation of alloy characteristics were each cut along the central axis thereof and the resultant cross sections were mirror-finished. On the central axis of the mirror-finished cross section, the thickness of stacked cemented carbide layers each, i.e., the thickness of each coating layer, was measured by means of an optical microscope. [0087]
  • It is noted that sample AA was insert-[0088] chip substrate 10 itself without coating layer that was used for comparison.
  • It was confirmed that the samples for tool evaluation each had a semispherical cutting edge with a radius of 7 mm. Then, an [0089] end portion 49 of each sample was partially cut away so as to make the height of the completed insert chip equal to the length of the original insert-chip substrate 10. The samples for tool evaluation were each press-fit into the leading end of a rock drill, used to drill a hole in granite. An impact test was performed for 5 hours under the conditions that the impact energy was 25 J/shot and the number of shots was 2000/min. After the test, for each sample, the amount of wear in the longitudinal direction of the sample as well as whether any breakage or crack was present or not were checked.
  • Results of this test are shown in Table 13. [0090]
    TABLE 13
    DRILL TEST RESULTS OF SAMPLES AA-LL
    Wear amount
    Sample (mm) Damage etc. to sample after test
    *AA  6 normal wear
    *BB  5.1 1st layer peeled in 2 hours
    CC 1.3 normal wear
    DD 0.4 normal wear
    EE 0.5 normal wear
    FF 0.4 normal wear
    GG 0.2 normal wear
    HH 0.2 normal wear
    II 0.2 normal wear
    JJ 0.3 normal wear
    KK 0.9 normal wear
    LL 1.1 normal wear
  • NINTH EMBODIMENT
  • Referring to FIG. 8, a structure of an oil-drilling tricone bit according to a ninth embodiment of the present invention is described. This oil-[0091] drilling tricone bit 50 has, as shown in FIG. 8, a plurality of rotatable cones 52 attached to an end portion of a body 51. Three cones 52 are usually attached to one body 51, and cones 52 are arranged with respective tops that are directed inward and face each other. A plurality of insert chips 53 serving as cutting edges respectively are each inserted from the outer surface of associated cone 52 and secured there. Insert chip 53 here is any of the insert chips described in connection with the first to seventh embodiments.
  • The structure of the oil-drilling tricone bit is illustrated in FIG. 8 by way of example only. The oil-drilling tricone bit intended by the present invention may be any, if the tricone bit has any of insert chips described in connection with the first to seventh embodiments. Thus, the shape, number and arrangement of cones as well as the shape of the body are not limited to those shown in FIG. 8. [0092]
  • Oil-[0093] drilling tricone chip 50 includes insert chips arranged respectively as cutting edges, and a high abrasion resistance is achieved by the outermost cemented carbide coating layers of the insert chips while an improved chipping resistance is achieved by other coating layers and the insert-chip substrate. It is thus possible for the oil-drilling tricone bit to exhibit a high performance in drilling of rocks that are at greater depths and thus hard to drill and still have a long lifetime.
  • According to the present invention, the insert chip includes the outermost cemented carbide layer which is one of cemented carbide coating layers each having an appropriate thickness at the tip portion of the cutting edge of the insert chip. The outermost cemented carbide layer has a higher hardness than that of other coating layers and the insert-chip substrate. Accordingly, it is possible to achieve a high abrasion resistance by the outermost cemented carbide layer and simultaneously achieve a high chipping resistance by other coating layers and the insert-chip substrate. Moreover, the thermal stress is reduced by intermediate layers, which prevents peeling and crack of coating layers. The oil-drilling tricone bit having such insert chips is thus appropriate for drilling of hard-to-drill rocks. [0094]
  • Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims. [0095]

Claims (14)

What is claimed is:
1. An insert chip of an oil-drilling tricone bit comprising:
an insert-chip substrate made of a cemented carbide of a first composition, said substrate including a cylindrical body and a cutting edge for drilling; and
a cemented carbide coating layer formed of at least two stacked coating layers made of a cemented carbide of a composition different from said first composition, said cemented carbide coating layer covering at least 80% of surface area of said cutting edge of said insert-chip substrate, wherein
said coating layers each have a thickness, at a tip portion of said cutting edge, ranging from 0.1 mm to 2.5 mm and, the total thickness of said cemented carbide coating layer ranges from 1 mm to 5 mm, and
said coating layers include an outermost cemented carbide layer and at least one coating layer besides said outermost cemented carbide layer and said outermost cemented carbide layer has a hardness higher than that of said at least one coating layer and of said insert-chip substrate.
2. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
said cemented carbide coating layer covers the whole of said cutting edge.
3. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
said at least two stacked coating layers include, besides said outermost cemented carbide layer, an anti-chipping layer of a composition with a higher Co content than that of said outermost cemented carbide layer or with a larger WC particle size than that of said outermost cemented carbide layer.
4. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
said at least two stacked coating layers include, besides said outermost cemented carbide layer, an anti-chipping layer of a composition with a higher Co content than that of said insert-chip substrate.
5. The insert chip of an oil-drilling tricone bit according to claim 4, wherein
said anti-chipping layer contains Co particles including special Co particles each elongated in the radial direction of said insert chip in a vertical cross sectional structure of said insert chip and each having a ratio ranging from 3 to 100 that is the length in the radial direction of the insert chip/the length in the axial direction of the insert chip, and said special Co particles constitute at least 5% by volume of the Co particles contained in said anti-chipping layer.
6. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
said outermost cemented carbide layer contains WC of an average particle size of at most 1 μm.
7. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
said outermost cemented carbide layer includes compressive residual stress.
8. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
said outermost cemented carbide layer includes compressive residual stress ranging from 0.05 GPa to 0.80 GPa.
9. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
only said outermost cemented carbide layer among said coating layers contains diamond particles of a particle size ranging from 10 μm to 100 μm and said diamond particles constitute 5% to 40% by volume of said outermost cemented carbide layer.
10. The insert chip of an oil-drilling tricone bit according to claim 9, wherein
said diamond particles are each covered with at least one of refractory metal and ceramic of at most 1 μm in thickness.
11. The insert chip of an oil-drilling tricone bit according to claim 1, wherein
said outermost cemented carbide layer has a micro Vickers hardness of at least 15 GPa.
12. An oil-drilling tricone bit having as its cutting edge the insert chip of an oil-drilling tricone bit according to claim 1.
13. A method of manufacturing an insert chip of an oil-drilling tricone bit comprising:
an inserting step of inserting an insert-chip substrate into a die;
a stacking step of stacking, on said insert-chip substrate, cemented carbide powder to form a coating layer having a desired thickness after being sintered; and
a sintering step of performing electrical pressure sintering, by using a punch inserted into said die, said punch having a depressed end which matches in shape a protruded cutting edge of said insert chip, applying a 10 pressure ranging from 20 MPa to 50 MPa, and controlling the temperature of said punch within a temperature range from 1500° C. to 1800° C.
14. The method of manufacturing an insert chip of an oil-drilling tricone bit according to claim 13, wherein
in said sintering step, sintering is performed for a period ranging from 5 minutes to 20 minutes.
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US7513320B2 (en) * 2004-12-16 2009-04-07 Tdy Industries, Inc. Cemented carbide inserts for earth-boring bits
US8109349B2 (en) * 2006-10-26 2012-02-07 Schlumberger Technology Corporation Thick pointed superhard material
US7740414B2 (en) 2005-03-01 2010-06-22 Hall David R Milling apparatus for a paved surface
US7665552B2 (en) * 2006-10-26 2010-02-23 Hall David R Superhard insert with an interface
US8637127B2 (en) 2005-06-27 2014-01-28 Kennametal Inc. Composite article with coolant channels and tool fabrication method
US7687156B2 (en) 2005-08-18 2010-03-30 Tdy Industries, Inc. Composite cutting inserts and methods of making the same
US7836973B2 (en) * 2005-10-20 2010-11-23 Weatherford/Lamb, Inc. Annulus pressure control drilling systems and methods
EP2024599B1 (en) 2006-04-27 2011-06-08 TDY Industries, Inc. Modular fixed cutter earth-boring bits and modular fixed cutter earth-boring bit bodies
US20070274794A1 (en) * 2006-05-26 2007-11-29 Cirino Thomas J Oblique angle serration location and drive interface
US7717654B2 (en) * 2006-05-26 2010-05-18 Cirino Thomas J Drill tip with serrated and dowel pinned shank interface
US7950746B2 (en) 2006-06-16 2011-05-31 Schlumberger Technology Corporation Attack tool for degrading materials
US7568770B2 (en) 2006-06-16 2009-08-04 Hall David R Superhard composite material bonded to a steel body
US8622155B2 (en) 2006-08-11 2014-01-07 Schlumberger Technology Corporation Pointed diamond working ends on a shear bit
US8033616B2 (en) * 2006-08-11 2011-10-11 Schlumberger Technology Corporation Braze thickness control
US7992944B2 (en) * 2006-08-11 2011-08-09 Schlumberger Technology Corporation Manually rotatable tool
US7722127B2 (en) 2006-08-11 2010-05-25 Schlumberger Technology Corporation Pick shank in axial tension
US8500210B2 (en) * 2006-08-11 2013-08-06 Schlumberger Technology Corporation Resilient pick shank
US7600823B2 (en) * 2006-08-11 2009-10-13 Hall David R Pick assembly
US8485609B2 (en) 2006-08-11 2013-07-16 Schlumberger Technology Corporation Impact tool
US8453497B2 (en) * 2006-08-11 2013-06-04 Schlumberger Technology Corporation Test fixture that positions a cutting element at a positive rake angle
US7997661B2 (en) 2006-08-11 2011-08-16 Schlumberger Technology Corporation Tapered bore in a pick
US7637574B2 (en) 2006-08-11 2009-12-29 Hall David R Pick assembly
US7475948B2 (en) 2006-08-11 2009-01-13 Hall David R Pick with a bearing
US8215420B2 (en) 2006-08-11 2012-07-10 Schlumberger Technology Corporation Thermally stable pointed diamond with increased impact resistance
US7390066B2 (en) * 2006-08-11 2008-06-24 Hall David R Method for providing a degradation drum
US7635168B2 (en) 2006-08-11 2009-12-22 Hall David R Degradation assembly shield
US7648210B2 (en) 2006-08-11 2010-01-19 Hall David R Pick with an interlocked bolster
US7669674B2 (en) 2006-08-11 2010-03-02 Hall David R Degradation assembly
US9051795B2 (en) 2006-08-11 2015-06-09 Schlumberger Technology Corporation Downhole drill bit
US7946657B2 (en) 2006-08-11 2011-05-24 Schlumberger Technology Corporation Retention for an insert
US8714285B2 (en) 2006-08-11 2014-05-06 Schlumberger Technology Corporation Method for drilling with a fixed bladed bit
US7320505B1 (en) 2006-08-11 2008-01-22 Hall David R Attack tool
US8007051B2 (en) 2006-08-11 2011-08-30 Schlumberger Technology Corporation Shank assembly
US8500209B2 (en) * 2006-08-11 2013-08-06 Schlumberger Technology Corporation Manually rotatable tool
US8201892B2 (en) * 2006-08-11 2012-06-19 Hall David R Holder assembly
US7387345B2 (en) 2006-08-11 2008-06-17 Hall David R Lubricating drum
US8567532B2 (en) 2006-08-11 2013-10-29 Schlumberger Technology Corporation Cutting element attached to downhole fixed bladed bit at a positive rake angle
US8414085B2 (en) * 2006-08-11 2013-04-09 Schlumberger Technology Corporation Shank assembly with a tensioned element
US8123302B2 (en) 2006-08-11 2012-02-28 Schlumberger Technology Corporation Impact tool
US8136887B2 (en) * 2006-08-11 2012-03-20 Schlumberger Technology Corporation Non-rotating pick with a pressed in carbide segment
US9145742B2 (en) 2006-08-11 2015-09-29 Schlumberger Technology Corporation Pointed working ends on a drill bit
US7410221B2 (en) * 2006-08-11 2008-08-12 Hall David R Retainer sleeve in a degradation assembly
US7963617B2 (en) 2006-08-11 2011-06-21 Schlumberger Technology Corporation Degradation assembly
US7871133B2 (en) 2006-08-11 2011-01-18 Schlumberger Technology Corporation Locking fixture
US8590644B2 (en) * 2006-08-11 2013-11-26 Schlumberger Technology Corporation Downhole drill bit
US7669938B2 (en) 2006-08-11 2010-03-02 Hall David R Carbide stem press fit into a steel body of a pick
US8292372B2 (en) 2007-12-21 2012-10-23 Hall David R Retention for holder shank
US8449040B2 (en) 2006-08-11 2013-05-28 David R. Hall Shank for an attack tool
KR101438852B1 (en) 2006-10-25 2014-09-05 티디와이 인더스트리스, 엘엘씨 Articles Having Improved Resistance to Thermal Cracking
US7347292B1 (en) 2006-10-26 2008-03-25 Hall David R Braze material for an attack tool
US8960337B2 (en) * 2006-10-26 2015-02-24 Schlumberger Technology Corporation High impact resistant tool with an apex width between a first and second transitions
US9068410B2 (en) 2006-10-26 2015-06-30 Schlumberger Technology Corporation Dense diamond body
US8512882B2 (en) * 2007-02-19 2013-08-20 TDY Industries, LLC Carbide cutting insert
US7401863B1 (en) 2007-03-15 2008-07-22 Hall David R Press-fit pick
US7846551B2 (en) 2007-03-16 2010-12-07 Tdy Industries, Inc. Composite articles
US9051794B2 (en) 2007-04-12 2015-06-09 Schlumberger Technology Corporation High impact shearing element
US7594703B2 (en) * 2007-05-14 2009-09-29 Hall David R Pick with a reentrant
US7926883B2 (en) 2007-05-15 2011-04-19 Schlumberger Technology Corporation Spring loaded pick
US8038223B2 (en) * 2007-09-07 2011-10-18 Schlumberger Technology Corporation Pick with carbide cap
US7832808B2 (en) 2007-10-30 2010-11-16 Hall David R Tool holder sleeve
US20110254349A1 (en) 2007-12-21 2011-10-20 Hall David R Resilent Connection between a Pick Shank and Block
US8540037B2 (en) 2008-04-30 2013-09-24 Schlumberger Technology Corporation Layered polycrystalline diamond
US7628233B1 (en) 2008-07-23 2009-12-08 Hall David R Carbide bolster
US8025112B2 (en) 2008-08-22 2011-09-27 Tdy Industries, Inc. Earth-boring bits and other parts including cemented carbide
US8322465B2 (en) 2008-08-22 2012-12-04 TDY Industries, LLC Earth-boring bit parts including hybrid cemented carbides and methods of making the same
GB0819257D0 (en) * 2008-10-21 2008-11-26 Element Six Holding Gmbh Insert for an attack tool
US8061457B2 (en) 2009-02-17 2011-11-22 Schlumberger Technology Corporation Chamfered pointed enhanced diamond insert
US8322796B2 (en) * 2009-04-16 2012-12-04 Schlumberger Technology Corporation Seal with contact element for pick shield
US8701799B2 (en) * 2009-04-29 2014-04-22 Schlumberger Technology Corporation Drill bit cutter pocket restitution
US8272816B2 (en) 2009-05-12 2012-09-25 TDY Industries, LLC Composite cemented carbide rotary cutting tools and rotary cutting tool blanks
US9050673B2 (en) * 2009-06-19 2015-06-09 Extreme Surface Protection Ltd. Multilayer overlays and methods for applying multilayer overlays
US8308096B2 (en) 2009-07-14 2012-11-13 TDY Industries, LLC Reinforced roll and method of making same
US8440314B2 (en) * 2009-08-25 2013-05-14 TDY Industries, LLC Coated cutting tools having a platinum group metal concentration gradient and related processes
US9643236B2 (en) 2009-11-11 2017-05-09 Landis Solutions Llc Thread rolling die and method of making same
US10005672B2 (en) 2010-04-14 2018-06-26 Baker Hughes, A Ge Company, Llc Method of forming particles comprising carbon and articles therefrom
SA111320374B1 (en) 2010-04-14 2015-08-10 بيكر هوغيس انكوبوريتد Method Of Forming Polycrystalline Diamond From Derivatized Nanodiamond
US9205531B2 (en) 2011-09-16 2015-12-08 Baker Hughes Incorporated Methods of fabricating polycrystalline diamond, and cutting elements and earth-boring tools comprising polycrystalline diamond
EP2571647A4 (en) 2010-05-20 2017-04-12 Baker Hughes Incorporated Methods of forming at least a portion of earth-boring tools, and articles formed by such methods
US8261471B2 (en) 2010-06-30 2012-09-11 Hall David R Continuously adjusting resultant force in an excavating assembly
SG187826A1 (en) 2010-08-13 2013-03-28 Baker Hughes Inc Cutting elements including nanoparticles in at least one portion thereof, earth-boring tools including such cutting elements, and related methods
US8728382B2 (en) 2011-03-29 2014-05-20 David R. Hall Forming a polycrystalline ceramic in multiple sintering phases
US8668275B2 (en) 2011-07-06 2014-03-11 David R. Hall Pick assembly with a contiguous spinal region
US8800848B2 (en) 2011-08-31 2014-08-12 Kennametal Inc. Methods of forming wear resistant layers on metallic surfaces
CA2848733A1 (en) 2011-09-16 2013-03-21 Baker Hughes Incorporated Methods of fabricating polycrystalline diamond, and cutting elements and earth-boring tools comprising polycrystalline diamond
US9016406B2 (en) 2011-09-22 2015-04-28 Kennametal Inc. Cutting inserts for earth-boring bits
GB201118739D0 (en) 2011-10-31 2011-12-14 Element Six Abrasives Sa Tip for a pick tool, method of making same and pick tool comprising same
US9140072B2 (en) 2013-02-28 2015-09-22 Baker Hughes Incorporated Cutting elements including non-planar interfaces, earth-boring tools including such cutting elements, and methods of forming cutting elements
JP2014196616A (en) * 2013-03-29 2014-10-16 三菱マテリアル株式会社 Drilling bit
US9790375B2 (en) * 2013-10-07 2017-10-17 Baker Hughes Incorporated Protective coating for a substrate
JP6468507B2 (en) * 2013-11-28 2019-02-13 国立研究開発法人産業技術総合研究所 PDC cutter for well drilling and PDC bit for well drilling
JP6696242B2 (en) * 2015-03-19 2020-05-20 三菱マテリアル株式会社 Drilling tip and drilling bit
JP6653841B2 (en) * 2015-03-31 2020-02-26 株式会社クボタ Manufacturing method of sliding member
WO2017015311A1 (en) * 2015-07-22 2017-01-26 Smith International, Inc. Cutting elements with impact resistant diamond body

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4694918A (en) * 1985-04-29 1987-09-22 Smith International, Inc. Rock bit with diamond tip inserts
SE505461C2 (en) 1991-11-13 1997-09-01 Sandvik Ab Cemented carbide body with increased wear resistance
US5370195A (en) 1993-09-20 1994-12-06 Smith International, Inc. Drill bit inserts enhanced with polycrystalline diamond
JP2896749B2 (en) 1994-12-16 1999-05-31 イーグル工業株式会社 Drilling bit and manufacturing method thereof
US5541006A (en) 1994-12-23 1996-07-30 Kennametal Inc. Method of making composite cermet articles and the articles
JPH1112090A (en) 1997-06-25 1999-01-19 Sekiyu Kodan High strength cvd diamond for digging bit and its production
US6220375B1 (en) * 1999-01-13 2001-04-24 Baker Hughes Incorporated Polycrystalline diamond cutters having modified residual stresses

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060166615A1 (en) * 2002-01-30 2006-07-27 Klaus Tank Composite abrasive compact
US20070186483A1 (en) * 2002-01-30 2007-08-16 Klaus Tank Composite abrasive compact
US20050257963A1 (en) * 2004-05-20 2005-11-24 Joseph Tucker Self-Aligning Insert for Drill Bits
US8505655B1 (en) 2005-01-17 2013-08-13 Us Synthetic Corporation Superabrasive inserts including an arcuate peripheral surface
US20090272583A1 (en) * 2005-01-17 2009-11-05 Us Synthetic Corporation Superabrasive inserts including an arcuate peripheral surface
US8272459B2 (en) * 2005-01-17 2012-09-25 Us Synthetic Corporation Superabrasive inserts including an arcuate peripheral surface
US8109350B2 (en) * 2006-01-26 2012-02-07 University Of Utah Research Foundation Polycrystalline abrasive composite cutter
US20090218146A1 (en) * 2006-01-26 2009-09-03 University Of Utah Research Foundation Polycrystalline Abrasive Composite Cutter
US7469972B2 (en) * 2006-06-16 2008-12-30 Hall David R Wear resistant tool
US20070290546A1 (en) * 2006-06-16 2007-12-20 Hall David R A Wear Resistant Tool
WO2009149071A3 (en) * 2008-06-02 2010-06-17 Tdy Industries, Inc. Cemented carbide-metallic alloy composites
WO2009149071A2 (en) * 2008-06-02 2009-12-10 Tdy Industries, Inc. Cemented carbide-metallic alloy composites
EP2653580A1 (en) * 2008-06-02 2013-10-23 TDY Industries, LLC Cemented carbide-metallic alloy composites
US8790439B2 (en) 2008-06-02 2014-07-29 Kennametal Inc. Composite sintered powder metal articles
EP3339562A1 (en) * 2010-06-24 2018-06-27 Baker Hughes, a GE company, LLC Cutting elements for earth boring tools, earth boring tools including such cutting elements, and methods of forming cutting elements for earth boring tools
CN103946405A (en) * 2011-11-01 2014-07-23 钴碳化钨硬质合金公司 Earth boring cutting inserts and earth boring bits including the same
US9551190B2 (en) 2011-11-30 2017-01-24 Mitsubishi Materials Corporation Excavation tool
CN102528942A (en) * 2011-12-28 2012-07-04 福建万龙金刚石工具有限公司 High-efficiency diamond bit and production process thereof
WO2014005834A1 (en) * 2012-06-20 2014-01-09 Element Six Abrasives S.A. Cutting inserts and method for making same
US10071355B2 (en) 2012-06-20 2018-09-11 Element Six Abrasives S.A. Cutting inserts and method for making same
US9428967B2 (en) 2013-03-01 2016-08-30 Baker Hughes Incorporated Polycrystalline compact tables for cutting elements and methods of fabrication
US10094173B2 (en) 2013-03-01 2018-10-09 Baker Hughes Incorporated Polycrystalline compacts for cutting elements, related earth-boring tools, and related methods
CN104047548A (en) * 2013-03-13 2014-09-17 江雨明 Diamond drill tooth with cobalt content gradient
KR20170086525A (en) * 2014-11-27 2017-07-26 미쓰비시 마테리알 가부시키가이샤 Drill tip and drill bit
KR102446207B1 (en) 2014-11-27 2022-09-21 미쓰비시 마테리알 가부시키가이샤 Drill tip and drill bit
KR20170102265A (en) * 2015-01-14 2017-09-08 미쓰비시 마테리알 가부시키가이샤 Drill tip and drill bit
KR102528631B1 (en) 2015-01-14 2023-05-03 미쓰비시 마테리알 가부시키가이샤 Drill tip and drill bit
US10900293B2 (en) 2016-04-20 2021-01-26 Mitsubishi Materials Corporation Drilling tip, drilling tool, and method of manufacturing drilling tip

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